Metal core composite filaments



Oct. 10, 1961 A. BREEN' 3,003,223

mm. CORE cou osm FILAHENTS Filed larch 25, 1957 4 Sheets-Shoot 1INVENTOR v ALVIN L. BREEN ATT RNEY Oct. 10, 1961 A. L. BREEN METAL CORECOMPOSITE FILAIENTS 4 Shuts-Sheet 2 Filed larch 25, 1957 .n w w w w lolw4oz w H ,7 M m INVENTOR ALVIN L. BREEN 10, 1961 A. L. BREEN 3,003,223

METAL CORE COMPOSITE FIMIEN'L'S Filed larch 25, 1957 & Sheets-Shoot 3 1Q F|G.l2

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INVBVIOR ALVIN L. BREEN A. L. BREEN METAL CORE COMPOSITE FILAI ENTS Oct.10, 1961 4 Sheets-Sheet 4 Filed March 25, 1957 FIG. I7

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ALVIN BREEN S at s METAL CORE COMPOSITE FILAMENTS Alvin L. Breen, WestChester, Pa., assknor' to E; I. du Pont de Nemours and Company,Wilmington, Del., a corporation of Delaware Filed Mar. 25, 1957, No.648,375

- 16 Claims. (Cl. 2 8 -82) This inventionisconcerned with filaments ofsynthetic polymers having "a metal core. I J

' The use ofspolymers as electrical'insulators on wire is wellkno wn.Such polymers have been applied to preformed wires from a solutionof thepolymer, from a dispersionofthe polymer followed by coalescence orfusion and from amelt ofthe polymer. p I

The first procedure referred'to above has thefdisadvantage that removalof'the solvent is time-consuming and costly and it is also difiicult'toproduce uniform coats of satisfactory thickness free from pin holes.Furthermore, such aprocess does not lend itself to the application ofcertain desirable insulating coatings such as polyarnides and polyesterswhich are known for their toughness and good physical properties,because of the lack of volatile non-corrosive solvents whichcan beconveniently and safely used with such polymers.v

'Iheapplication of polymers to electrical conductors by means of theirdispersions is also difiicult and, if the particles, are to ,becoalesced by an organic liquid, the same ditliculties are present as inthe solution method of application. This method is usually limited tothe application of very thin coatings unless the coating proc possibleis limited to. the amount of draw given to the metal and is generallynot in excessof l0%'draw,.tlm percentof draw being the percent of the:length that is permanently added (i.e., not regained onrelease of thedrawing tension) during the drawing operation.

It has also'been proposed to make decorative ribbon by laminating a thinmetal film between two plastic films and then slitting to strips. 'Byits very nature such a process is very time consuming and expensive, andis applicable only to relatively large denier ribbon} Itis an object ofthis invention to produce articles comprising a metal core surrounded bya synthetic poly mer sheath, --It, is a further object of this inventionto produce continuous fine. filaments'ofa synthetic polymer having ametal core. A further'object is concernedwith the production of suchfilaments inthe deniers used in the textile arts. Other objectswillappear hereinafter;

ess is repeated a number of times, in which case the com- I positecoating may not be sufliciently uniform.

Y The other method of coating which has been used in the past is theapplication of g a melt of the polymer onto a preformed wire. In suchprocesses, however it is diffieult to center the wire accurately enough'to obtain uniform coatings.

With respect to those known coating processes which use heat,i.e., thoseinvolving fusion of polymer particles or the utilizing of coatings inthe form of melts, such processes have been limited to productscontaining preformed wire having a melting point sufiiciently above thatof the polymer so that the wire would remain intact during the coatingprocess.

Another serious limitation with the previous methods of coatingelectrical conductors is the fact in the case of very fine wires theirhandling during the coating operation as well as the proper applicationof the coating, are quite difficult. Many types of conductors that wouldbe of great utility if coated, do not lend themselves to conventionalcoating processes because of their inherent weakness when in the form ofvery small diameter Furthermore, in order'to' obtain very fine wires,longand expensive wire drawing and annealing steps are required therebyadding considerably to the cost of the final iusulated product; i v

It is known to eject afmixtureof a molten metal and a fiber-formingpolymer into an air jet to produce short, curled filaments withirregular and nonuniform structure but such process does not relate tothe making of filaments having a definite skin, and core component. tThe most desirable physical properties of polymers such as polyamidesand polyesters are obtainedby ori:

The objects of this invention have been attained bysimultaneouslyextruding a molten, synthetic, linear, fiberforming,orientable polymer and a molten metal through a spinneret as acontinuous sheath and core respectively of a composite filament andorienting the polymeric sheath to the desired extent by a drawingoperation. The metal core of the drawn filament is preferably less than0.031 inch in its largest diameter perpendicular to its length withpreferably a uniform cross-section along the length, of the filament andcomprises a metalthat melts at or below the temperature at which thepolymer or its solution is extruded,

In the drawings:

FIGURE 1 is atop plan view of the upper plate or filter pack of aspinnerct used in the practice oi this invention; "FIGURE 1(a) is anelevation view in cross-section of the upper plate or filter pack takenalong the lines la-la of FIGURE 1. The right-hand half of FIGURE 1(a) isan elevation in cross-section along the plane of the right-hand half ofline 1a-la of FIGURE 1 and the left-handhalf of FIGURE 1(a) is anelevation in' cross-sectionalong the plane of theleft-hand half of linela -1a of FIGURE 1. It will be noted that the two portions of line 1a-1aof FIGURE 1 form an angle at the center of the figure. The two halves ofFIGURE 1(a) have been assembled in this fashion in order :10 showtheshape and direction of the dilierent holes and cavities even though theymay not fall along the central plane of the spinneret; V FIGURE Z'is abottom plan view of the apparatus or FIGURE 1 taken at a somewhatdifferent angle than FIGURE 1, line la-la of FIGURE 2 likewise showingthe dual plane cut of FIGURE 1(a); FIGURE 3 is a top plan view of thebottom plate of a spinner-ct usedin the practice of this invention;

FIGURE 4 is an elevation view in cross-section of the bottom spinneretplate shown in FIGURE 3 with the right-hand half. shown in the'plane ofthe right-handhnlf of line of FIGURE 3 '(drawn to the center) section,of the upper and lower plates of FIGURES l,

1(a),i 2; 3, and 4, in assembled position utilin'ng the showing ofFIGURE 4 for the lower plate and the m ing of co-aeting parts of FIGURES1, 1(a) and Zinc the upper plate or, filter pack. Here g the drain, withtheoemer line indicated as in FIGURE, 4, the

URE 6; v FIGURE 8 is a cross-section taken on line 88 of FIGURE 6;

FIGURE 9 is a cross-section taken on 9-9 of FIG- URE 6;

FIGURE 10 is a view in cross-section showing the detailso'f the lowerportion of the pin shown in. FIG- URE'6 while in operative position inthe lower plate of FIGURES 3 and 4;

FIGURES 11-19 inclusive are schematic representations of filaments inlengthwise and cross-sectional view made in accordance with theinvention. In all instances polymeric sheath 100 surrounds metal corematerial 101.

It can be seen from the drawings that top plate 1 of the spinneretadapted to receive the filter pack (not shown), has a central chamber 2and an annular chamber 3 separated from each other by wall 4. In thebottom of chamber 2 are a plurality of holes 5 passing downwardlythrough plate 1 and diverging outwardlyfrom each other. Holes 5 leadinto shallow annular groove 6 formed in the top surface of lower plate 7which, in assembling the spinneret, is fastened to plate 1 as describedbelow. Holes 8 lead from the bottom of annular chamber 3 verticallydownward through plate 1 and terminate at groove 6 of the lower plate 7.Pins 9, provided with longitudinal passages 10 therethrough arepositioned in holes 8 with a press fit (and may be further fastened inplace by a spline or other means for insuring a tight fit, if desired)with the upper ends of pins 9 extending above the bottom of annularchamber 3 as shown. The press fit of pins 9 may be supplemented by theaction of circular serrations 11 provided at the top of pins 9 to gripthe inside of holes 8.

Pins 9 are circular in cross-section in the portion 12 in contact withholes 8, as shown in FIGURE 7, having a diameter sufiicient to give apress fit in holes 8, pins 9 in the major portion 13 passing throughplate 7, having a cross-section which is partly arcuate (as shown at 13)but which has, as by cutting the pin to form chords in the cross-sectionof the pins, the general shape of a mutilated triangle as shown inFIGURE 8. Pin 9 then tapers at 14 near its lower part to a smaller,partially arcuate (as shown at 14') but generally mutilated triangularcross-section as shown in FIGURE 9 of the next lower portion of pins 9being necked down at 15 (to form an annular groove) and terminating in ashort annular cylindrical section 16 somewhat larger in diameter thanneck portion 15 as shown in FIGURES 6 and 10, with the ends of 'pins 9being flush with the outer face of plate 7 and with holes 10 terminatingin orifices 17. Plate 7 is formed with holes 18 passing through plate 7,holes 18, which are tapered at their lower ends, having a circularcross-section throughout equal in diameter to the arcuate portions ofsections 13 and 14 of pins 9 to insure a tight fit between thecontacting surfaces.

It will be noted that annular orifice 19 is formed at the outer surfaceof plate 7 by the clearance between orifice 18 of the plate 7 and theouter and smaller cylindrical portion 16 of pin 9. The total area of theouter end of orifice 18 (inclusive of orifice 17 and the annularcylindrical portion 16 of pin 9) is collectively referred to as theextrusion orifice designated as 20 in the drawings.

Plates 1 and 7 are fastened with threaded bolts 21 passing through holes22 in plate 7 with the bolt heads r 4 plate 1. After the plates 1 and 7are assembled and fastened in place by bolts 21, proper alignment isassured by insertion of tapered pins 25 of round cross-section having adrive-fit into tapered holes 26 of plate 7 and registering tapered holes27 of plate 1, the ends of pins 25 being drawn into position above andclear of the outer surface of plate 7.

Gaskets 28 and 29 are inserted in plate 7 prior to assembling thespinneret and are pressed in place as shown respectively into circulargrooves 30 and 3 1 (gasket 28 being additionally pressed into acorresponding circular groove 32 in plate 1) when plates 1 and 7 arefastened together, so as to prevent leakage of the polymer fluid, metalor gas between the plates.

The apparatus is connected with suitable piping and filter packs (notshown) as required to supply a molten polymer and a molten metal to thespinneret.

In the melt-spinning processes preferred in the practice of thisinvention, 'molten metal flows from annular chamher 3 throughlongitudinal passages 10 of pins 9 and out of the spinneret as the coreof the composite filament. Molten polymer flows from central chamber 2through holes 5 into annular groove 6 (through which pins 9 pass)downwardly through the passages in plate 7 formed by the clearancebetween the pin (at its non-arcuate periphery) and hole 18 of plate 7(shown clearly in FIGURE 10 which represents pin 9 in plate 7 turnedfrom its position in FIGURE 6 in order to show the clearance between pin9 and plate 7), then along the groove formed at neck 15 and outwardly asa sheath through annulus 19.

It is, of course, understood that the design af apparatus is capable ofconsiderable variation. Thus pins 9, instead of being non-circular incross-section within plate 7, may be circular in cross-section withsuflicient clearance being provided between the pins 9 and holes 18 topermit passage of the polymer around the pins 9 as a sheath. In theexamples, the relative viscosity (71f) i.e., the viscosity of a solutionof polymer relative to that of the solvent is used as the measure of themolecular weight. The polyamide solutions contained 5.5 grams of polymer3 in 50 ml. of 90% formic acid and the viscosity was measured at 25 C.The polyester solutions contained 2.15

g. of the polymer in 20 ml. of a 7/10 mixture by weight oftrichlorophenol/phenol and the viscosity was measured at 25 C. a

The following examples in which parts, proportions 4 and percentages areby weight unless otherwise indicated,

are intended to illustrate this invention and in no manner It) limit it.

I Example I A spinneret similar to that shown in FIGURES l to 10 of'thedrawings was constructed with only one hole in which the outsidediameter of the extrusion orifice 20 was 0.030 inch, the outsidediameter of the end 16 of tube 9 near the orifice was 0.022 inch indiameter and the inside diameter of the tube 9, i.e., the diameter ofbeing received in counterbore 23 and abutting at their 7 orifice 17, was0.011 inch. Using this spinneret, poly- (ethylene terephthalate) ofrelative viscosity 30 and the binary eutectic mixture of tin and leadhaving a melting point of 181 C. were simultaneously spun at 270-275" C.into a stream of air at 30 C. moving in a direction concurrently withthe path of travel of the formed filament. Straight filaments having acontinuous uniform core of metal completely and uniformly surrounded by'a covering of the polyester were produced.

- Example 11 I spasms V URELI (one filament) andFIGURE 12 (severalmaments) respectively. The ends ot the metalcore of a two feet lengthofthe as-spu'n yarn were silvered to facilitate making connections andelectrical measurements made. The yarn had a resistance of 100 ohms perfoot and carried a current of 0.10 ampere for an indefinite period oftime without causing any change in appearance of the polymeric sheath ormaking the composite filament hot. Under a current of 0.125 ampere themetallic core fused apart. This yarn, as spun, was drawn 100% in a 125C. oil bath by hand to give a strong filament with a continuous metalcore having an average diameter of about 0.003 inch completelysurrounded by a uniform polyester sheath. 'The as-spun filaments couldnot be drawn at room temperature since the core broke at av lowelongation and the'sheath soon after. A filament prepared in a similarmanner but with about 28% core could be drawn at room temperature 150%.

The core fractured into segments. A filament with an oriented sheath anda similarly segmented core wasalso made by cold drawing a similarfilament with a 33% core.

Ema. m

A spinneret similar to that used in. Example II was used to spin asheath ofthe polyester. previously used around the core of an alloycomprising 48% bismuth, 28.5% lead, 14.5% tin and 9.0% antimony meltingover the range 103-227 C. and having an ultimate elongation of less than1% at room. temperature. The molten poly-. mer and molten metal weresimultaneously spun as sheath and core respectively at 288 C. into airat room temperature and the yarn wound up at 500 yards per minute. Thecontinuous filaments produced had a continuous core completely anduniformly surrounded by a sheath of poly(ethylene terephthalate) similarto the filament of FIGURE 11 but with thecore comprising approximatelyby volume of the cross-section of each filament. A sample of the yarnwas drawn 160%" (i.e., drawn yarn was. 260% of original undrawn length)in a 135 C. oil bath to yield filaments with continuous anduniform.rnetal cores having a tensile strength of 18,000 pounds persquare inch, an ultimate elongation (permanent potential furtherelongation at break under standard elongation testing conditions) of287% and a denier per filament of 85.

A 370% draw in a 125 C. oil bath gave anyarn in which the core was justbroken into tiny segments completely enclosed by the sheath. A 220% drawat 90 C. gave broken segments of the core in conjunction with hollowspaces in the yarn, a longitudinal view of the yarn section being shownin FIGURE 13. A 220% draw at 75 C. gave a yarn in which the metalliccore had been broken into tiny segments and the surrounding polymersheath had necked down at the points where the core had broken, so that.each filament had alternate thick and thin portions.

Example IV Using a one-hole spinneret similar to that used in Example IIpoly(ethylene terephthalate) of relative viscosity 37 was melt-spun as asheath around the molten core of the alloy which comprises 40% bismuthand tin melting over the range 139-170 C. The composite filaments werespun at 290 C. and at 130 yards per min- However; a:

ute into a l-foottubeot water at 33C. whichwas pumped concurrently withthe direction of the thread motion. Spinning wasz-good andcontln'u'ousfilaments were obtained, atypical filament s diameter of 0.009 inch anda core 0.006 inch in diameter which is equivalent to 45% core by volume,being otherwise similar to FIGURESll and 12. v V

A portion of the as-spun yarn was hand-rolled along (the length of thefilament with a metal roller 1 temperature to yield ribbon-shapedfilaments mately 0.050 inch wide; similar in appearance to thefiattenedfilaments shownin FIGURE 14. As shownin FIGURE 14, certain ofthe filaments were notfiattened' since the pressure of the hand-rollerwas not, in this case,

etfectively applied to all filaments. The rolling did not break thesheath or separate the two components and the resulting ribbon had amuch higher degree of reflectivity than the dull appearing as-spunyarn,so that itpresented a glittering shiny surface. The rolling producedanincrease in length equivalent to a 30% elongation of the as-spunfiber. The product had a. tensile strength of 10,400 pounds per squareinch.

The as-spun filament could be elongated a maximum of 3.7% withoutbreaking the core by. drawing at room temperature alone but acombination of rolling and drawing" permitted an overall elongation of35% without breaking the core. f; 7

Example V Roly(ethylene terephthalate) of relative .viscosity 37 and tinmaintained at 285 and 280 C- respectively were melt-spun as the sheath84% and core 16% by volume respectively of a composite filament withaspinneret similar to that shown in FIGURES 1-10 but with only' onespinning orifice. Themonofilament was extruded down from the spinneretthrougha two inch airspace at ambient temperature into a l foot, longtube ofwater at constant head of pressure at 30 C. that flowedconcurrently with the filament. Good spinning was enjoyed and thefilament was continuously wound up at 1:21 yards'per minute. The as-spunfilament (0.0085 inch in diameter) of 800 denier. per filament had atensile strength of 8,300

' pounds per square inch (0.32 g.p.d.) andan ultimate elongation of648%. The filaments had a shiny, continuous, tin corecompletely'surroundedfby polymer.

7 A sample of the filament was. elongated 400% by drawing over a pin atroom temperature. This treatment fractured the. core into smalllongitudinal segments'so that the filament resembled that shown inFIGURE 13 i with a diameter of about 0.0045 inch. Hand-rolling'of thedrawn yarn with a metal roller flattened the filament and afiorded adecorative ribbon 0.017 inch'wide and 0.002 inch thick with shinyglittering sequin-like segments of tin (0.012 inch wide, 0.0015 inchthick and 0.10 inch apart) in the core completely surrounded by apolyester sheath with an appearance similar to that-of FIGURE 19.Physical properties of these products are given below;

Tensile Ultimate Treatment Tenacity, Strength, Elo a- Ml Denier] g.p.d.p.s.1. tlon, er: Filament cent As-spun 0. 32 8, 300 648 9. 6 8101Drawing 2.1 54,600 18 29 161 Drawing plus rolling 1. 6 41, 300 14 27 108Mi as'used herein signifies initial modulus in grams per denier.

Another sample of the same as-spun yarn as above was rolled with a metalroller to give an increase in length equivalent to a 70% elongation ofthe original length. The flattened filament with a continuous metal corehad a cross-section similar to those shown in FIG- URE 15. The rolledfilament was then drawn over a pin atroom temperature togive a total.elongation of 250% of the filaments as-spunlength. The drawn fila- 7ment had a continuous metal core and its cross-section resembled that ofFIGURE 16 where it can be noted that the filament apparently drew up incross-section away from'a ribbon shape. Rolling of the drawn filamentflattened the filament once more and gave a ribbon 0.010 inch wide and0.002 inch thick with a continuous uniform sheath of polyestercompletely surrounding a continuous core of tin about 0.006 inch wideand 0.0008 inch thick similar to FIGURE 17. All these filamentsdisplayed a bright shiny core but the reflectivity was much greater withthe rolled filaments. Physical properties of these products are givenbelow:

It was quite surprising that the above sequence of roll-. ing anddrawing allowed the tin core to be elongated to a total'of 250% sincethe core of the as-spun yarn fractured when elongated 23% by drawingwithout prior rolling. When it was attempted to roll and draw a lengthof cast tin similar to the core of the above filament, the tin drewabout 30% before breaking after being increased in length 10% byrolling.

Example VI The polymer of Example .V was replaced withpoly(hexamethylene adipamide) of relative viscosity 41, and sheath-corefilaments spun as before. The as-spun filaments (which were 0.0076 inchin diameter) containing 70% core by volume were elongated 20% by rollingand then drawn over a pin at room temperature to an overall elongationof 190% of the as-spun length without fracturing the core. The rolledand drawn filaments had a flattened cross-section similar to FIGURE 18,being about 0.008 inch by 0.0017 inch in cross-section, and displayed areflective, continuous metal core completely surrounded by the polyamidesheath. The rolled and drawn filaments had a tenacity of 0.76 g.p.d.(tensile strength of 42,800 p.s.i.), an ultimate elongation of 31%, a Mi(initial modulus) of 12 g.p.d. and a denier per filament of 391.

The polyamide was replaced with linear polyethylene of 4.7 melt index(ASTM Std. DI238-52T) density of 0.96 and melting point of 150 C. and afilament spun by extruding the polyethylene at 250 C. simultaneouslywith the molten tin at 60 yards per minute into a water quench as inExample V. Lengths of the filaments containing a continuous tin corecompletely surrounded by a sheath of polyethylene could be elongated 60%by drawing after first elongating the filaments 30% by rolling.

In the drawings, it is desired to point out that the small black specksoccurring in the various views of filament cross-sections, e.g., FIGURES14l7 and 19, represent the media used in mounting the filaments in thepreparation of filament specimens to be photographed.

The metal core of the filaments of this invention can be any metal thatis molten at a temperature at which the polymer for the sheath isstable. Such metals include tin, lead, bismuth, lithium, selenium andtheir alloys with each other and such metals as an antimony and zinc asfor example, bismuth solder, battery plate, white metal, aluminumsolder, and eutectic alloy to name a few.

For the sheath of the filaments of this invention any fiber-formingpolymer that can be spun into filaments at a temperature at which themetal core is molten can be used such as polyesters, polyamides,polyethers, polyacetals, polyurethanes, polyureas, polyhydrocarbons asApril 19, 1955, or spun by wet-spinning or dry-spinning methods, from asolution of a polymer component and the molten metal. Also, dispersionspinning methods (as in the case of polytetrafluoroethylene) can be usedwhere desired.

Although the composite filaments of this invention having continuousmetal cores can be used in an as-spun condition made without anyintentional drawing during the spinning, it is generally preferable toincrease their strength by orientation of the sheath. The temperature ofdrawing can be modified up to the melting point of the polymer so as toattain the maximum elongation of the metal. A part or all of theelongationobtained by such temperature drawing, of course, can bereplaced by drawing during the spinning in which case the filaments arewound up at a rate much greater than that at which they are extrudedfrom the spinneret. Filaments with cores of some metals having a highextensibility can be drawn at room temperatures, while with others atemperature near or above the melting point of the metal needs to beused.

It has been found that greater extensibility of the metal core withoutfracturing can be obtained in some cases if a combination of rolling anddrawing is used in sequence. These steps can be combined as, forexample, by drawing a filament through a slit afforded by the smoothedges of two rods that squeeze the filament at a constant pressure.

In spinning the filaments of this invention, a relatively rapid rate ofquenching is preferred in order to solidify the polymer and so preventpossible formation of globules of metal in the core due to the surfacetension of the molten metal. Such quenching can be accomplished by aflow of gas or by spinning into a liquid, preferably at a temperature of080 C.

The filaments of this invention having intermittent seg ments of metalin the core can be made by drawing a composite filament under suchconditions that the metal core fractures. In general, this can be doneat tempera-' tures below the melting point or minimum value of themelting temperature range of a metal. The total elongation of thefilament in the draw must exceed the ultimate elongation of the metal.This will vary from metal to metal, but in general, the elongationnecessary, which may range from 50 to l500%, to produce the desiredstrength in the polymeric sheath will be sufficient to fracture themetal in the as-spun filaments. In order to provide enough strength forthe polymer to hold its form during the drawing step, the sheath of theas-spun filament should comprise about 5 to .of the fiber volume, withthe range of 25 %95% sheath being preferred. The total force to breakthe core must be less than the force required to break the sheath.Knowing the tensile strengths of the metal and the polymer at thedrawing temperature, the core to sheath ratio can be adjusted to alforda segmented core by drawing. A given ratio of filament components isobtained with a given spinneret by adjusting the flow rates of the twoliquids that are spun, as for example, by changing the polymer feed pumprate or by altering the air pressure that might be used, for example, toextrude the molten metal.

With some metals having a sufiiciently high surface tension, it ispossible to obtain an intermittent core by drawing the filaments attemperatures above the melting 9 point of the metal so that the metalcontracts into segments in the core. In other cases, this same result isattained in spinning if the qucnchingis sufiiciently slow.

:While the invention may be applied over a wide range of denier, it ispreferred that, the filaments as spun have a denier of 20 to 4,000 andthat the drawn filaments have a denier of 2 to 2,000.

The filaments of this invention are of advantage in textile applicationsdue to their strength and appearance. Those filaments with continuous orintermittent reflective cores can be used to make all manner of novel.fabrics.

, The appearance of the filaments can be altered byIco spinning dyes orpigments in'the polymer sheath or by Those filaments with continuousmetal cores can be used as insulated conductors and those having smalldiameter cores of low melting metals are useful as microampere fuses.Fabrics made of the filaments of this invention can be used to provideshielding around electronic equipment. The solubilities andthermoplasticities of the.

polymeric sheaths can be used to coalesce the contacting edges of thefilaments in a fabric, for example, into a form-stable covering thatwill not be displaced by vibration of the equipment and yet reduce theusual electronic noise. 1

Although reference has been made herein to the making of flat,ribbon-like filaments by rolling metal core filaments of this invention,no claim is made in this application to such flattened filaments ortheir production (although they are embraced within the broadscope .ofthe present invention) since they form the subject matter of the patentapplication of Robert W. Bundy Serial No. 648,374 entitled CompositeFilaments and Their Manufacture filed of even date herewith. Also,,.thespecies represented by a flattened fractured core and its preparationform the subject matterof the said patent application of Robert W.Bundy.

Since the invention is capable of considerable variation beyond as wellas inclusive of the illustrations given herein, it will be understoodthat any modification which conforms to the spirit of the invention, isalso intended to be included within the claims.

I claim as my invention:

1. A shaped article comprising a metal core and an adherent oriented.polymer sheath disposed about said core, said metal core having amelting point below the temperature at which the polymer for the sheathbecomes unstable. I

2. A shaped article comprising a metal core and an adherent orientedsheath of synthetic linear polymer .of uniform diameter disposed aboutsaid core, said metal core having a melting point below the temperatureat which the polymer for the sheath becomes unstable.

3. A shaped article comprising a metal continuous core and an adherentoriented sheath of synthetic linear polymer of uniform diameter disposedabout said core, said tur; at which the polymer for the sheath becomesunsta le.

4. A shaped article comprising a metal discontinuous core and anadherent oriented sheath of synthetic linear polymer of uniform diameterdisposed about said core, said-metal core having a melting point belowthe temperature at which the polymer for the sheath becomes unstable. r

5. A textile filament comprising a shaped article comprising a metalcore and an adherent oriented sheath of synthetic linear polymerdisposed about said core, said metal core having a melting point belowthe temperature at which the polymer for the sheath becomes'unstable. g6. The article of claim 5 characterized in that the composite filamenthas a denier between 2 and 2,000.

7. The article of claim 5 in which the sheath com- I prises 5%-95% ofthe filament.

8. The article of claim 5 in which the sheath comprises 25 %-95 of thefilament.

9. A shaped article comprising a metal core and an adherent orientedsheath of synthetic linear polymerof uniform diameter disposed aboutsaid core, said metal core having a melting point below the meltingpoint of the polymer for the sheath.

10. A textile filament comprising a shaped article com prising a metalcore and an adherent oriented sheath of.

synthetic linear polymer disposed about said core, said metal corehaving a melting point below the melting point of the polymer for thesheath. 7 g 7 11. A textile filament comprising a metal core and anadherent oriented polyester sheath disposed about said core, said metalcore having a melting point below the temperature at which the polymerfor the sheath becomes unstable.

'12. The filament of claim 11 wherein the polyester sheath ispoly(ethylene terephthalate).

. 13. A textile filament comprising a metal core and an adherentoriented polyamide sheath disposed about said core, said metal corehaving a meltingpoint below the metal core having a melting point belowthe tempera- 7 temperature at which the polymer for the sheath becomesunstable.

14. The filament of claim 13 wherein the polyamide sheath ispoly(hexamethylene adipamide).

15. A textile filament comprising a metal core andan 1 adherent orientedaddition polymer sheath about said core, said metal core having amelting point below 'the'temperature at which the polymer for the sheathbecomes unstable.

16. The filament of claim 15 wherein the addition polymer sheath ispolyethylene.

References Cited in the file of this patent UNITED STATES PATENTS

1. A SHAPED ARTICLE COMPRISING A METAL CORE AND AN ADHERENT ORIENTEDPOLYMER SHEATH DISPOSED ABOUT SAID CORE, SAID METAL CORE HAVING AMELTING POINT BELOW THE TEMPERATURE AT WHICH THE POLYMER FOR THE SHEATHBECOMES UNSTABLE.